ANALYSIS OF PROTON MAGNETIC RESONANCE SPECTRA OF MONOSUBSTITUTED BENZENES .I. ADDITIVITY RULE FOR RING PROTON COUPLING CONSTANTS

A complete analysis of the high resolution proton magnetic resonance spectraof monosubstituted benzenes has been performed as an AA′BB′C spin system, and the chemical shifts as well as the coupling constants are determined for 20 kinds of the compounds with great accuracy. The magnitude of each coupling constant is plotted against the electronegativity of the substituents, and empirical relations between the coupling constant and the electronegativity are given. An additivity rule for the coupling constants in the ring protons is presented, which permits an estimate of the ortho- and the meta-coupling constants in the disubstituted benzenes by making use of the ones in the monosubstituted derivatives. © 1968 Academic Press Inc.